Internal-combustion heater having means to prevent fuel contamination of the ventilating air



Jamil, 1949. A. WILLIAMS, JR 2,458,958

' INTERNAL-COMBUSTION HEATER HAVING MEANS TO PREVENT FUEL CONTAMINATION OF THE VENTILATING AIR Filed Nov. 6, 194:5

2 Sheets-Sheet l Jan. 11-, 1949. L. A. WILLIAMS, JR. 2,458,963

INTERNAL-COMBUSTION HEATER, HAVING MEANS TO PREVENT FUEL CONTAMINATION OF THE VENTILATING AIR Filed Nov. e, 1943 2 Sheets-Sheet 2 Patented Jan. 11, 1949 UNITED STATES F FICE v 1 2,458,968 INTERNAL-COMBUSTION HEATER" HAVING MEANS 'ro PREVENT FUEL CONTAMINA- rion. oErnE VENTILATING AIR Lynn Arwilliams, .Jr.,- Northfield, .Ill.,; assignor to. Stewart-Warner C'orporatiom; Chicago,- 111;, a

corporation of Virginia Application November 6, 1943-,,1Serial:No. 509 161 1. Q v p inventionrelates .to internal. combustion heaters of. the type particularly adapted. for. but.

notzlimitedto, usein heatingthe cabins, .and other bodying my invention and showing parts .cut

away to illustrate-detail of construction}; Fig; 2 is a transverse; irregularsectional: view taken on the'line 22 of Fig. 1-; and

Fig; 3'is a partial, sectional view of the nozzle assembly and is taken on the line 33 of Fig; 2;

Ihave illustrated my invention as comprising a heater casing Ill having-its lefthand'end attached toan airsupply pipe 12. which leads to a ram, blower, or any other suitable source of air supply.

The righthand or outlet end of the heater casing;

I0 is connected to a duct l4 leading to anraircraft cabin or other space or spaces-to be heated" with ventilating air furnished by'the-heater. It will be understood that' the duct M may haveone or more outlets and maybe provided with any usual or-desired 'arrangement of shutters-for controlling flow of ventilating air into the space or spaces supplied bythe heater.

The casing l0 encloses a heat exchanger I6 which may be of any suitable type, but which is' illustrated hereinasbeing of the spiraltypedisclosed and claimed in the. co-pending application of William C. Parrish, SeriaiNo.494',155;fi1ed July 1.0, I943, and assignedto the assignee of the present.

heat exchanger 16 and forms a conical combustion chamber'Zfl supplying-hot products of combustion to. the heat exchanger. flow through a spiral gas passage in the heatxchanger I6 and. are discharged. to. atmosphere through anexhaust outlet 22, as more iullyillus trated and described in the aioresaidEarrish application. The cone. l8; istencloseduin a sheet metal. housing 2.4 whichsurrounds this cone in. spaced. relation. thereto and. terminates in the rolled over. edgeZB.

application. A perforated cone [8 has its large end'attached to the lefthand or inlet end oi.

These hot gases 2*.Glaims. (Cl. 126-116) The casting; 28.1sweldedor otherwise secured to the. smaller ,endofthecone l8 and to the corresponding end of a cylindrical shell 30, welded or otherwise suitably secured to. the cone, and in effect. constituting a part thereof. This casting 28 is threaded as indicated.at -3 2 to receive a plug-likeielectrical igniter 34,-.having a resistance wire 36 in opencommunicationwith the interior of the cone: |8.- This-igniter. issuppliedwithcurrentthrough an. insulated conductor 38 having; one end attached to the igniterplug and theother end attached to' a terminal. '40 of a terminalbracket 32,- havingoutwardly turned: ends M attachedtothe casing I ll byrivets 45. The terminal plate or. bracket .42. al'sohasadditional terminals.

48andz50. V

, A nozzle-casting 52 ris.-removably secured to the; casting: 2&by1screwsz54a Thiscasting is threaded to;receive a-plug-likenozzle 56, including'a cylindricalstrainer. 58 for, removing impurities from.

the: fuel-beforethiswfuel. enters the nozzle. and; is.

discharged thereby, into, the combustion, chamber ZD in theform of a conical spray.' The strainer 581-is' located ina chamber; 60 formed-in the caste.

ing-52: and-supplied-with fuel through a restricted. inlet 62. ,Alstud 64 is threaded intoa boss 66= provided bythe casting 52. This'stud projects through; an opening in a cover .68 which is clampedzagainst thelefthandtend of the housing 1 2.4 by.- washer :10 andinut l2rscrewed onto the end of the -stud. v

The cover 68 and housing 24 provide a combus-. tion air space Ht-surrounding coneiir and thenoz-v Air zle and igniter. assembly secured thereto. fromthecombustion air space '14 passes through the perforations-in the cone Hi to mix with the fuel deliveredby the;nozzle.56 and form the-c om-. bustible mixture which is-burnedin the combus tion. chamber 20. Air for the combustion/air space- 14. is,-furnished-by a-combustionair supply pipe. indicated generally by the reference.characterJB. Thispipe includes-a metal elbow 18- at.

tached atone end by. acoupling BQJtoanipple 82 welded or. otherwise'secured to the housing:

2 i-andin openzcommunication with the interior of. this housing. The other end of the elbow 8' is clamped to one end-0i a; short section of flexible hose 8|, the-other end oiwhich isiclamped to a rigidpipe '83: leadingfrom any suitable source of combustion :air supply.

Thefuel rsupplyfline forthe nozzle 56 com prisesan:elbowrfi iathreadedinto the nozzle castthrough the nipple 82, coupling 80 and adja cent portion of the elbow 18 of the combustion air supply pipe. This elbow I8 is provided with a short sleeve 88 welded thereto and this sleeve snugly fits about the copper tubing 86 adjacent a point where it passes through wall of this elbow. One end of the copper tubing 86 is connected by a coupling 90 to a second section of copper tubing 92 leading to a solenoid valve 94 connected to a fuel supplypipe 96 leading from a fuel pump or any other suitable source of fuel under pressure.

The solenoid valve 94 is strapped to a bracket 98 suitably secured to thecasinglu and this bracket is illustrated as providing a clip H10 forming an intermediate support for the copper tubing. A conductor I02 connects the'solenoid valve to the terminal 48. A third conductor 104 is illustrated as being connected to the terminal 50 and this conductor may lead to any additional control means not shown. It will be understood that suitable circuits are connected to the terminals 40, 48 and 50 for supplying current to these terminals and such circuits may include thermal switches, manual switches and other usual control elements.

Particular attention is called to the fact that the fuel supply line for the nozzle 56 is surrounded by the air inlet pipe where this line extends across the ventilating air space between the casing l and the housing 24. This is important in that it prevents contamination of the ventilating air by fuel leaking from this fuel supply line. Any fuel which leaks from a portion of the fuel supply line adjacent the ventilating air passage between the heater casing l0 and housing 24- passes into the combustion air space 14 and vaporizes to mix with the combustion air delivered to the combustion chamber through the openings in the cone' I8. Attention is also called to the fact that the electrical conductor 38 for the igniter 34 also enters the housing 24 by way of the combustion air supply line. The elbow 18 has a grommet H36 surrounding an opening through which this conductor extends. This grommet closely fits the conductor to prevent or minimize leakage of combustion air from the combustion air supply pipe at this point. The points at which the electrical conductor 38 and copper tubing'86 pass through the wall of the elbow '18 are outside of the ventilating air stream so that slight leakage of combustion air at these pointsis immaterial, as such leakage will not tend to contaminate theventilating air.

The combustion air flowing through the combustion air supply pipe and chamber 14' con nected therewith will prevent overheating of the fuel flowing to'the nozzle 56 and will prevent vapor lock occurring in the section of the fuel supply pipe adjacent the nozzle. Where extreme cooling of this portion of the fuel supply line is desired, the combustion air supply pipe should be connected with a source of unheated air. However, where a heavy fuel is used or where, for other reasons, vapor lock is not a problem, the combustion air supply pipe may, if desired, be supplied with heated air from the duct M or from any other suitable source. I

A feature of my invention lies in the particular arrangement of thefuel nozzle and igniter relative to each other and to the combustion chamber so that heat from the igniter is transmitted to the nozzle during the starting period, but relatively little heat is transmitted to the nozzle from the combustion chamber While the heater is in normal operation. The casting 28 is preferably made of material having a high heat conductivity such as, for example, brass. This casting supports the igniter plug 34 and transmits heat therefrom to a point adjacent the end of the nozzle 56 which is surrounded by a tubular-like portion of this casting. This construction functions to conduct heat to the nozzle both by radiation from the adjacent portion of the casting 28 to the nozzle and by conduction through the nozzle casting 52 into which the nozzle is threaded. It will be understood that the igniter 34 is cut off from its source of current by the usual thermostatic switch after the heater has attained normal operating temperature so that heat is transmitted from the igniter to the nozzle only during the starting period.

The combustion air entering the interior of the housing 24 and the cover 58, which is in sealing engagement therewith, surrounds the cone l8 and nozzle and igniterassembly and absorbs heat therefrom during normal heater operation; furthermore, the nozzle is indirectly attached to the small end of the cone I8 through castings 52 and 28 and the former casting is preferably made of cast iron, or other material having a relatively low coefiicient of heat conductivity, Only a small part of the casting 28 is directly exposed to the combustion chamber, and a large part of the heat absorbed by this casting is conducted to the igniter plug 34 and shell 30 and dissipated therethrough; furthermore, the small end of the cone I8 is surrounded by a large body of combustion air which is flowing to the combustion chamber through the perforations in this cone, so that the end of the cone attached to the casting 28 is the coolest part of this cone. All of these factors combine to prevent excessive heating of the nozzle during burner operation, and thereby to prevent cracking of the fuel passing therethroug-h.

While I have illustrated and described only a single embodiment of my invention, it is to be understood that my invention is not limited to the particular details shown and described, but may assume numerous other forms, and that my invention includes all modifications. variations and equivalents coming within the following claims.

I claim:

1. An internal combustion heater of the class described, comprising a ventilating air casing, a heat exchanger located within said casing, a liquid fuel burner for supplyinghot gases to said heat exchanger including a fuel spray nozzle re-.

movably attached to one end of said burner, said burner being located within said casing at one end of said heat exchanger so as to provide space for ventilating air to flow through said casing around saidburner, a fuel line leading to said nozzle, a fitting exterior to said burner and within said casing for connecting said fuel line to said nozzle, a jacket forming a, combustion air space surrounding said burner and open at the rear end thereof to permit ready access to'said burner for insertion or removal of said nozzle, fitting, or fuel line, a detachable cap for closing the open end of said jacket and enclosing said fuel line and fit ting, a conduit for conducting combustion air to theinterior of said jacket and cap, said air conduit having its inlet end located remotely from said heater, and said fuel line being located inside said conduit between said cap and a point outside of said casing whereby said nozzle is easily removable forcleaning and whereby fuel leakage at said nozzle or fitting cannot contaminate the ventilating air flowing through said casing and heat exchanger and around said burner.

2. An internal combustion heater of the class described, comprising a ventilating air casing, a heat exchanger located within said casing, a liquid fuel burner for supplying hot gases to said heat exchanger including a fuel spray nozzle removably attached to one end of said burner, said burner being located within said casing at one end of said heat exchanger so as to provide passages for ventilating air to flow through said casing around said burner, a fuel line leading to said nozzle, a fitting exterior to said burner and within said casing for connecting said fuel line to said nozzle, means defining a, combustion airspace surrounding said burner and open at the rear end thereof to permit ready access to said burner for insertion or removal of said nozzle, fitting or fuel line, a detachable cap for closing said open end and enclosing said fuel line and fitting, an air pipe for supplying air for combustion to said burner, said pipe traversing the ventilating air casing between said combustion air space defining means and the exterior of said casing and terminating at a source of air remote from said heater and said fuel line being located inside said air pipe between said combustion air space defining means and a point outside of said casing.

LYNN A. WILLIAMS, Jn.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

